Drilling platform

ABSTRACT

A floating vessel suitable as a drilling platform in which the vessel has legs extending therethrough which in their upper position are tightly held by the vessel and each leg includes a footing which can be secured thereto or to the vessel when the legs are lowered to raise the vessel into operating position to provide the lower end of the legs with an extended bearing surface for engagement with the bottom.

llnite States ntent [72} inventors William 1111. Moore; George '1. Richardson; l loyd T. Pease, all

of Houston, Tex. {21] Appl. No. 819,623 [22] Filed Apr. 28, 1969 [45] Patented Dec.2l, 1971 [73} Assignee The Offshore Company Houston, Ten.

[54] DRlLlLlNG PLATFORM 11 Claims, 9 Drawing Figs.

[52] U.S.Cl 61/465, 254/ 107 [51] 11nt.Cl 1. E021) 17/00 [50] Field of Search 61/465; 254/106, 107

[56] References Cited UNITED STATES PATENTS 2,927,436 3/1960 Besse 61/465 12/1961 Suderow 61/465 3,277,653 10/1966 Foster 61/465 2,913,880 11/1959 Rechtin et al.. 61/465 3,479,828 11/1969 Luque 61/465 FOREIGN PATENTS 7 934,369 1963 GreatBritain 61/465 Primary Examiner-Jacob Shapiro Allorneys-J. Vincent Martin, Joe E. Edwards and Jack R.

Springgate mum] m2! 19H 3.628386 SHEET 1 OF 4 A770 EVJ DRILLING PLATFORM SUMMARY The present invention relates to an improved structure for marine drilling which is floatable and includes legs for raising the structure to its desired position for drilling.

An object of the present invention is to provide an improved drilling platform which provides stable footing under all conditions of the bottom which may be encountered at the drilling site.

Another object is to provide an improved drilling platform having legs which are tightly secured in their upper position to prevent vibration during movement of the platform.

Still another object of the present invention is to provide an improved drilling platform having tank footings which may alternately be secured to the hull and to the legs and which when secured to the hull, provide a minimum of drag to the movement of the platform through the water.

A still further object is to provide a vessel which includes its own propulsion for movement on water to a marine drilling site and may be jacked up on its legs to provide a stable drilling platform.

A further object is to provide an improved vessel which can be supported in drilling position on legs and which has a sufficiently low center of gravity to be stable when moving on the water.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention are hereinafter set forth and explained with reference to the drawings wherein:

FIG. I is a plan. view of a drilling platform vessel constructed in accordance with the present invention.

FIG. 2 is a side elevation of the drilling platform vessel shown in FIG. 1.

FIG. 3 is a detail partial sectional view of one leg showing the guides for the legs with the legs in their uppermost secured position.

FIG. d is a partial schematic view of the vessel and showing the improved leg and tank footing with the leg secured to the vessel and the tank footing in position for movement of the vessel on the water.

FIG. 5 is a similar schematic view of the vessel raised on the leg with the tank footing secured to the lower end of the leg to provide extended bearing surface for the lower end of the leg on the bottom.

FIG. 6 is another similar schematic view showing the vessel raised on the leg with the tank footing secured to the vessel.

FIG. 7 is an elevation view of ajoint connection in one of the legs. 7

FIG. 8 is a sectional view taken across one of the joints of the leg along line 8-8 in FIG. 7.

FIG. 9 is a sectional view of the joint shown in FIG. 8 taken along line 9-9.

DESCRIPTION OF THE PREFERRED EMBODIMENT The vessel It] may have its own propulsion system as shown in FIGS. II and 2. The vessel is provided with the legs 12 which are adapted to be lowered through the vessel It) with suitable jacking mechanisms. Also, the usual platform drilling equipment such as the derrick D and the cranes C are mounted on the vessel I0. While four legs 12 are shown, the vessel 10 may have three or more of such legs without departing from the spirit of the present invention. Each of the legs 12 extends through a well 14 in vessel It]. The lower portion of vessel 10 surrounding the wells 14 defines the recesses 16 in which the tank footings 18 are positioned during movement of the vessel 10 on the water. Each of the footings 18 is designed to receive the leg 12 therein or to allow the leg 12 to move therethrough.

As shown in FIG. 3, each of the wells 14 includes the lower guides 20 and the upper guides 22. The lower end of the legs 12are slightly larger than the remainder of the legs so that when the legs 12 are in their uppermost position they are held tightly within the wells 14. In this position the legs 12 are secured against movement and vibration during movement of vessel 10. To further secure the legs I2, suitable wedges 23 are inserted between the legs 12 and the upper guides 22.

The tank footings 118 each include the means 24 for releasably securing the footing to its associated leg 12 and the means 26 for releasably securing it to the vessel 10 within its recess 16. Additionally, the means 28 is provided to releasably secure the vessel 10 to each of the legs I2 and to positively move the legs 12 in both directions through their wells X4 in vessel 10. The means 28 includes the upper lock pins 30, the lower lock pins 32 and the usual jacking means (not shown) for moving the pins 30 and 32 relative to each other. The legs 12 each include interconnected structural members and the lower end of each of the legs 12 includes the integral tank footing 34.

The vessel 10 having its own propulsion is sailed to the drilling site with the tank footings I8 secured in the position shown in FIG. 4. The means 24 secures each tank footing 18 to the lower end of its leg I2 and the legs 12 are secured by the means 28 in their uppermost position so that the tank footings 18 are held within their respective recesses 16. If desired, the tank footings 18 may be held in their recesses 16 by the means 26 and the means 24 may be in their released position. This position of the tank footings 18 minimizes the drag which the footings cause during the movement of the vessel 10 through the water. With the vessel 10 in position over the preselected drilling site, the type of bottom determines whether the legs 12 should be lowered with the tank footings 18 thereon as shown in FIG. 5 or without the tank footings '18 as shown in FIG. 6. When the bottom is relatively soft and has a limited bearing capacity, the tank footings 18 are secured to the legs 12 as hereinafter described to provide sufficient bearing capacity to support the vessel 10in a raised position. If the bottom conditions are such that only a limited bearing area is needed to support the raised vessel, then the tank footings 18 are held secured to the vessel 10 in their recesses 16 while the legs 12 are lowered.

If it is desired to lower the tank footing 18 with each of the legs 12, the tank footings 18 are first secured to the vessel 10 by the means 26 and then their legs 12 are lowered a short distance to project a few feet below the lower surface of tank footing I8. Thereafter the means 24 are actuated to secure the tank footings 18 to their respective legs 12, and then the means 26 are released. The legs may then be positively moved downwardly with respect to the vessel 10. When the footings 34 and the tank footings l8 engagethe bottom, further relative movement of the legs 12 through the wells 14 raises the vessel 10 above the water to the position shown in FIG. 5. The projection of the lower end of the legs 12 below the lower surface of the tank footings 18 causes a greater penetration into the bottom and provides lateral stability. The extended lower surface of the tank footings 18 greatly increases the bearing area of the legs 12 in engagement with the bottom to thereby provide a greatly increased stability of the vessel 10 in its raised drilling position.

When the drilling site is over a bottom which is relatively hard, the extended bearing area of the tank footings 18 may not be desired. Under such conditions, the means 26 are actuated to secure the tank footings 18 to the vessel 10 in their respective recesses 16 and then the means 24 are released to allow the legs 12 to be positively moved downwardly through the wells 14 of vessel 10 and the tank footings 18. As shown in FIG. 6, when the footings 34 of legs 12 have firmly engaged the bottom, further jacking of the legs 12 through the vessel It) raises the vessel 10 above the water surface to provide a stable platform from which drilling operations may be conducted. V

The legs 12 normally are very long with a length of 350 feet being expected. Since the projection of the legs 12 below the vessel 10 would cause drag on the movement of the vessel and may even ground the vessel and the extension of the legs upwardly decreases the stability of the vessel, a portion of the legs 12 is made to be removable. This removable portion may be secured on the deck during movement of the vessel 10. FIGS. 7, 8 and 9 illustrate a joint between the removable section 36 and the main section 38. Each of the longitudinal members 40 of the main section 38 has a pin end 42 adapted to be received in the box end 44 on the longitudinal members 46 of the removable section 36. The pin end 42 is an upstanding tubular portion having a. reduced external diameter from member 46 and the box end 44 is a tubular section of increased thickness and an internal diameter slightly larger than the pin end 42. Securing means 48 is provided to maintain the pin end 42 in its desired position within the box end 44. When the removable section 36 has been secured to the main section 38, the whole structure functions as a unitary leg for supporting the vessel 10 as previously described.

The securing means 48 includes the arcuate locking segments 50, the screws 52 which control the position of the scgments 50, the grooves 54, defined around the interior of the box end 44 and the grooves 56 defined around the exterior of the pin end 42. When the segments 50 are retracted completely within grooves 54, then the securing means 48 is released and the section 36 may be removed from section 38. Actuation of screws 52 to move the segments 50 inwardly so that they are partially within grooves 56 and partially within grooves 54 locks the sections 36 and 38 together. The upper and lower edges of segments 50 are beveled to match with the tapered shape of grooves 56. Thus when the segments 50 are forced into the grooves 56, the bevels and tapers coact to bring the pin end 42 and box end 44 into the desired secured relationship with each other.

By having the removable sections 36 on the legs 12, the stability of vessel can be improved by storing the removable section 36 on the deck which lowers the center of gravity of vessel 10. Also this reduces the dynamic loading on legs 12 during movement of vessel 10.

From the foregoing description, it can be seen that the improved structure of the present invention provides a stable marine drilling platform in varied conditions of the bottom of the body of water at the drilling site. This structure makes available an extended bearing area which may be secured around the lower end of the legsto engage the bottom and thereby increase the stability of the structure. Additionally, the tank footings which provide this extended bearing area are releasably secured within recesses defined in the vessel so that drag during movement through the water is minimized and may be releasably secured to the recesses when thelegs are lowered through the vessel..The vessel has its own propulsion and is provided with wells having guides for the movement of the legs therethrough and the legs are slightly enlarged at their lower ends to fit tightly into the lower guides so that the legs and tank footings are held secure during movement of the vessel to prevent vibration of the legs.

What is claimed is:

l. A floatable structure suitable for drilling, comprising aself-propelled floating vessel,

a tank footing,

a leg,

said vessel and said tank footing defining aligned holes through which said leg may extend,

means for releasably securing said tank footing to said vessel,

means for releasably securing said tank to said leg, and

means for positively moving said leg through said vessel and said tank footing in both directions when said tank is secured to said vessel and for positively moving said leg, with said tank footing secured near the lower end thereof, through said vessel so that said vessel may be raised above the water with said tank footing secured thereto and with the tank footing secured to the lower end of said leg.

2.A floatable structure according to claim 1, wherein said vessel defines a recess on its underside,

said recess being of sufficient size to receive said tank footing whereby said tank footing when positioned in said recess during movement of said vessel on the water, creates a minimum drag.

3. A floatable structure according to claim 1, wherein said leg includes interconnected structural members, and a footing structure secured to said structural members at the lower end of said leg. I

4. A floatable structure suitable for drilling comprising a floating vessel,

a tank,

a leg,

said vessel and said tank defining aligned holes through which said leg may extend,

means for releasably securing said tank to said vessel,

means for releasably securing said tank to said leg,

means for positively moving said leg through said vessel in both directions, and

guide means in said hole through said vessel adapted to engage said leg,

said leg having an enlarged lower end whereby when it is in its uppermost position, it is tightly engaged by said guide means and when it is in a slightly lower position it may be moved freely through said guide means.

5. A floatable structure suitable for drilling, comprising a floating vessel,

' a tank,

said vessel and said tank defining aligned holes through which said leg may extend,

means for releasably securing said tank to said vessel,

means for releasably securing said tank to said leg,

means for positively moving said leg through said vessel in both directions,

upper guide means in said vessel adapted to guide the movement of said leg through said vessel, and

lower guide means in said vessel adapted to guide the movement of said leg through said vessel,

the lower end of said leg being enlarged to have a tight fit within said lower guide whereby when said leg is in its uppermost position, the leg is tightly held by said lower guide.

6. A floatable structure according to claim 5, including wedge means positioned between said upper guide and said leg to secure said leg with respect to said upper guide.

7. A floatable structure suitable for drilling, comprising a self-propelled floating vessel,

said vessel defining a plurality of recesses on its underside,

a plurality of tank footings adapted to be received in said recesses,

said recesses being of sufficient size to receive the entire tank footings therein and to thereby minimize the drag against movement of said vessel,

a plurality of legs,

said vessel and said tank footings defining aligned holes through which said legs may extend,

means for releasably securing said tank footings in said recesses,

means for releasably securing each one of said tank footings to one. of said legs, and

means for positively moving said legs through said vessel in both directions,

said tank footings when secured to said legs and said legs moved downwardly below said vessel being connected near the lower end of said legs to provide extended bearing area for said legs,

said tank footings being retained within said recesses unattached to said legs when the water bottom is sufficiently firm to support said vessel in elevated position on said legs.

8. A floatable structure according to claim 7, each of said legs includes,

a removable section, and

means for securing said removable section to the remaining portion of the leg.

9. A floatable structure according to claim 3 wherein each of said legs includes longitudinal members,

a pin and box joint between each of the longitudinal members of said legs and said removable section.

10. A floatable structure according to claim 9 wherein said securing means includes,

a plurality of segments, a plurality of mating annular grooves in said pin and box joint,

said segments adapted to be wholly contained within one of 10 said grooves, and

means for moving said segments so that they are partially in each of two mating grooves to secure said pin and box joint.

ill. A floatable structure suitable for drilling, comprising a floating vessel,

a plurality of legs,

means for providing relative movement between said vessel and each of said legs, each of said legs having a removable section and means for securing the removable section to the remaining portion of the leg, the legs and removable sections each including longitudinal members and structural members interconnecting said longitudinal members, a pin and box joint between each of the longitudinal members of said legs and said removable sections, at least one annular groove in each of the pin and box ends of said joints, a plurality of segments adapted to be wholly contained within one of said grooves, and means for moving said segments so that they are partially in each of two mating grooves to secure said pin and b0 joint.

i l t 

1. A floatable structure suitable for drilling, comprising a self-propelled floating vessel, a tank footing, a leg, said vessel and said tank footing defining aligned holes through which said leg may extend, means for releasably securing said tank footing to said vessel, means for releasably securing said tank to said leg, and means for positively moving said leg through said vessel and said tank footing in both directions when said tank is secured to said vessel and for positively moving said leg, with said tank footing secured near the lower end thereof, through said vessel so that said vessel may be raised above the water with said tank footing secured thereto and with the tank footing secured to the lower end of said leg.
 2. A floatable structure according to claim 1, wherein said vessel defines a recess on its underside, said recess being of sufficient size to receive said tank footing whereby said tank footing when positioned in said recess during movement of said vessel on the water, creates a minimum drag.
 3. A floatable structure according to claim 1, wherein said leg includes interconnected structural members, and a footing structure secured to said structural members at the lower end of said leg.
 4. A floatable structure suitable for drilling comprising a floating vessel, a tank, a leg, said vessel and said tank defining aligned holes through which said leg may extend, means for releasably securing said tank to said vessel, means for releasably securing said tank to said leg, means for positively moving said leg through said vessel in both directions, and guide means in said hole through said vessel adapted to engage said leg, said leg having an enlarged lower end whereby when it is in its uppermost position, it is tightly engaged by said guide means and when it is in a slightly lower position it may be moved freely through said guide means.
 5. A floatable structure suitable for drilling, comprising a floating vessel, a tank, a leg, said vessel and said tank defining aligned holes through which said leg may extend, means for releasably securing said tank to said vessel, means for releasably securing said tank to said leg, means for positively moving said leg through said vessel in both directions, upper guide means in said vessel adapted to guide the movement of said leg through said vessel, and lower guide means in said vessel adapted to guide the movement of said leg through said vessel, the lower end of said leg being enlarged to have a tight fit within said lower guide whereby when said leg is in its uppermost position, the leg is tightly held by said lower guide.
 6. A floatable structure according to claim 5, including wedge means positioned between said upper guide and said leg to secure said leg with respect to said upper guide.
 7. A floatable structure suitable for drilling, comprising a self-propelled floating vessel, said vessel defining a plurality of recesses on its underside, a plurality of tank footings adapted to be received in said recesses, said recesses being of sufficient size to receive the entire tank footings therein and to thereby minimize the drag against movement of said vessel, a plurality of legs, said vessel and said tank footings defining aligned holes through which said legs may extend, means for releasably securing said tank footings in said recesses, means for releasably securing each one of said tank footings to one of said legs, and means for positively moving said legs through said vessel in both directions, said tank footings when secured to said legs and said legs moved downwardly below said vessel being connected near the lower end of said legs to provide extended bearing area For said legs, said tank footings being retained within said recesses unattached to said legs when the water bottom is sufficiently firm to support said vessel in elevated position on said legs.
 8. A floatable structure according to claim 7, each of said legs includes, a removable section, and means for securing said removable section to the remaining portion of the leg.
 9. A floatable structure according to claim 8 wherein each of said legs includes longitudinal members, a pin and box joint between each of the longitudinal members of said legs and said removable section.
 10. A floatable structure according to claim 9 wherein said securing means includes, a plurality of segments, a plurality of mating annular grooves in said pin and box joint, said segments adapted to be wholly contained within one of said grooves, and means for moving said segments so that they are partially in each of two mating grooves to secure said pin and box joint.
 11. A floatable structure suitable for drilling, comprising a floating vessel, a plurality of legs, means for providing relative movement between said vessel and each of said legs, each of said legs having a removable section and means for securing the removable section to the remaining portion of the leg, the legs and removable sections each including longitudinal members and structural members interconnecting said longitudinal members, a pin and box joint between each of the longitudinal members of said legs and said removable sections, at least one annular groove in each of the pin and box ends of said joints, a plurality of segments adapted to be wholly contained within one of said grooves, and means for moving said segments so that they are partially in each of two mating grooves to secure said pin and box joint. 